BIOL239 Chapter Notes - Chapter 4: Consanguinity, Mendelian Inheritance, Penetrance

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coffeeherring584

20 Jul 2016

School

University of Waterloo

Department

Biology

Course

BIOL239

Professor

Christine Dupont

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Document Summary

An allele is dominant if it ahs the same phenotypic effect in heterozygotes as in homozygotes. Sometimes heterozygote have a phenotype different from its parent, this is called incomplete dominance. Heterozygotes that have more than one allele contributing independently to the phenotype of the heterozygous is called codominant. An example of this is the m and n antigens found in blood, where heterozygous may have both antigens in its blood. Genes can have more than two alleles. For example, the coat colour of rabbits and blood types have many kinds of alleles. When neither the a or b antigen is present, the blood type is o. A and b are codominant to each other (producing ab blood type) while the o is recessive to them. Blood type o can only occur when it is homozygous. A mutant allele is created when an existing allele changes to a new genetic state, a process called mutation.

Related Questions

QUESTION 1

Jim is blood type A, his brother John is type O and his sister Jane is type AB. What are the genotypes of their parents?

Which of the following is true for alleles that show incomplete dominance?

Heterozygotes have a genotype like the dominant allele.

Homozygotes have a genotype like the recessive allele.

Heterozygotes have a phenotype intermediate between the dominant and recessive alleles.

Homozygotes have the same phenotype as the heterozygotes.

QUESTION 3

Which principle of inheritance concluded that when games are formed in meiosis, the two alleles of each gene separate from one another, and each gamete receives only one allele?

independent assortment

Which term best describes a condition in which alleles at one locus can alter the expression of alleles at another locus?

polygenic inheritance

A single unit of genetic information located on a chromosome defines:

The physical expression (appearance or function) of an organism's genes defines:

genotype

a single characteristic

Palomino horses (golden color with a blond mane) are an incompletely dominant trait produced by the combination of the chestnut color allele and the cream color allele. If you wanted to produce as many palominos as possible, which mating strategy below would be the best choice?

Which term best describes the effect of a single gene on multiple aspects of the phenotype?

polygenic inheritance

QUESTION 9

Which term best describes the separate expression of both alleles for a single trait in the same cell?

polygenic inheritance

QUESTION 10

One form of a gene found on a single chromosome defines:

A chocolate lab (whose mother was a yellow lab) is mated with a black lab whose genotype is BbEe. What fraction of the offspring would be expected to be yellow labs?

What type of allele is always expressed regardless of whether the individual is homozygous or heterozygous for it?

Both the dominant and recessive alleles

Given the parents AABBGgHhrr Ã AabbGgHhRr, assume simple dominance and independent assortment. What proportion of the progeny will be expected to have the genotype AaBbggHHrr?

___________________ is defined as having two of the same type of allele for a particular trait.

The physical position of an allele on a single chromosome defines:

Which term best describes two or more genes affecting the phenotype in an additive fashion?

codominance

polygenic inheritance

In need of assistance. Please help answer the following.

1) Pure-breeding yellow guinea pigs crossedwith pure-breeding white guinea pigs produce only cream-coloredoffspring. This pattern indicates incomplete dominance. Rough hairis found to be dominant to smooth hair. Give the F1 and F2genotypic and phenotypic ratios of a cross of a smooth white guineapig with a homozygous rough yellow guinea pig.

2) A breeder of cattle has a herd of white cowsand a roan bull. Hair color in this breed is controlled by anincomplete dominant gene. The two homozygous forms are either redor white, and the heterozygous is roan. Answer the followingquestions please

What color calves are expected and in whatproportion?

Outline a procedure to develop an all-redherd.

3) In horses, black coat color is influenced bythe dominant allele (B), and chestnut coat color is influenced bythe recessive allele (b). Trotting gait is due to a dominant gene(T), pacing gait to the recessive allele (t). If a homozygous blacktrotter is crossed with a chestnut pacer:

What will be the appearance of the F1 and F2generations?

Which phenotype will be the most common?

Which genotype will be the most common?

Which of the potential offspring will be certain tobreed true?

4) In garden peas, one pair of alleles controlsthe height of the plant and a second pair of alleles controlsflower color. The allele for tall (D) is dominant to the allele fordwarf (d), and the allele for purple (P) is dominant for the allelefor white (p). A tall purple crossed with a tall purple produces Â¾tall purple and Â¼ tall white. What is the genotype of the parents?

5) Three alleles control the ABO blood types.I^A and I^B are codominant genes, so thecombination of I^AI^B produces the AB bloodtype. The third allele I^ois recessive to the other twoalleles. Indicate which of these parents could produce the givenchild and submit your response to the instructor.

A X AB produce B child.

A X O produce A child.

A X B produce O child.

A X AB produce O child.

A X AB produce B child.

B X B produce O child.

AB X AB produce A child.

goldspider471

___1. Nationally, the most common cause of Down Syndrome is
a. nondisjunction of Chromosome 21 during meiosis
b. translocation of Chromosome 21 onto another chromosome
c. inversion of a large section of Chromosome 21
d. deletion of the Down Syndrome gene
___2. In humans, sex is determined by
a. The presence or absence of the Y chromosome
b. The ratio of X chromosomes to sets of autosomes
c. The temperature during fetal development
d. Which parent is stronger at the time of conception
___3. A translocation is
a. a chromosomal abnormality in which a piece of one chromosome breaks off and attaches to a different chromosome
b. an abnormality in which the chromosomes are translocated out of the nucleus
c. a condition in which the chromosome has broken in two places and come back together with the middle segment backward
d. an abnormality in which there is an extra copy of one chromosome
___ 4. In snapdragons, a red-flowered plant crossed with a white-flowered plant produces all pink-flowered offspring. But crossing two pink-flowered plants produces red, pink, and white in a 1:2:1 ratio. This is a good example of
a. Incomplete dominance
b. Dominance of the red allele over the white allele
c. Lethal effects of the pink allele
d. Sex-linkage of the flower-color alleles
___ 5. If a person with type AB blood marries a person with Type O blood, what blood types are possible in their children? (Assume this trait is a single-gene trait, not complicated by interaction with other genes).
a. A, B, AB, or O
b. A or B only
c. AB or O only
d. AB only 2
___6. In what phase of meiosis are haploid nuclei first formed? a. Anaphase I b. Metaphase II c. Telophase II d. Metaphase I e. Telophase I
___7. What is the phenotype of a heterozygous tall pea plant? a. tall b. Tt c. TT d. tt e. dominant
___ 8. If genes A and B are far apart on a chromosome, and A and C are close together, which of the following observations is expected?
a. Crossing over will occur more often between A and C than between A and B
b. Crossing over will occur at equal frequencies between A and C, and between A and B
c. Crossing over will occur more often between A and B than between A and C
___9. Sometimes an organismâs genotype for one gene masks the effect of a different gene. This phenomenon is called
a. Dominance
b. Incomplete dominance
c. Co-dominance
d. Epistasis
e. Variable expressivity
___10. The dominant allele of a gene is
a. The one that is expressed most often in a population
b. The one that is expressed most often in any particular cross
c. The one that is expressed in an individual that has two different alleles
d. The one that is most healthy to have, that gives the greatest fitness
___11. In human cells, DNA replication occurs
a. In S phase of interphase
b. In G1 phase of interphase
c. In G2 phase of interphase
d. In prophase of mitosis
e. Whenever the cell needs to read the DNA to make proteins
___ 12. A process in which recipient cells take up genes from DNA molecules floating free in the surrounding medium is called
a. conjugation
b. specialized transduction
c. generalized transduction
d. transformation 3
___ 13. Most calico cats are female. However, a few rare males are observed. What is the genotype of a male calico cat?
a. X BX 0
b. X OY
c. X BY
d. X BYY
e. X BX OY
___ 14. A type of red-green color-blindness is a sex-linked (X-linked) recessive trait in humans. Can a woman have this type of color-blindness?
a. Yes, a woman could be color-blind if her mother and father were both heterozygous.
b. Yes, a woman could be color-blind but only if she has an abnormal number of sex chromosomes.
c. No, women can't show sex-linked traits because they lack a Y chromosome.
d. No, women can't show sex-linked traits because they have two X chromosomes.
e. Yes, a woman could be color-blind if her father was color-blind and her mother was a carrier (heterozygous).

BIOL239 Chapter Notes - Chapter 4: Consanguinity, Mendelian Inheritance, Penetrance

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